PHP count instances of array items in a string

Question

In PHP 7.3:

Given this array of low relevancy keywords...

$low_relevancy_keys = array('guitar','bass');

and these possible strings...

$keywords_db = "red white"; // desired result 0
$keywords_db = "red bass"; // desired result 1
$keywords_db = "red guitar"; // desired result 1
$keywords_db = "bass guitar"; // desired result 2

I need to know the number of matches as described above. A tedious way is to convert the string to a new array ($keywords_db_array), loop through $keywords_db_array, and then loop through $low_relevancy_keys while incrementing a count of matches. Is there a more direct method in PHP?

There is no more direct method in PHP.

revo
– revo

2020-03-29 21:18:11 +00:00
Commented Mar 29, 2020 at 21:18 — revo
– revo, Commented Mar 29, 2020 at 21:18
BTW I don't call it tedious.

revo
– revo

2020-03-29 21:23:32 +00:00
Commented Mar 29, 2020 at 21:23 — revo
– revo, Commented Mar 29, 2020 at 21:23

Casimir et Hippolyte · Accepted Answer · 2020-03-29 22:07:43Z

2

The way you described in your question but using array_* functions:

echo count(array_intersect(explode(' ', $keywords_db), $low_relevancy_keys));

(note that you can replace explode with preg_split if you need to be more flexible)

or using preg_match_all (that returns the number of matches):

$pattern = '~\b' . implode('\b|\b', $low_relevancy_keys) . '\b~';

echo preg_match_all($pattern, $keywords_db);

demo

answered Mar 29, 2020 at 22:07

Casimir et Hippolyte

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1 Comment

chillywilly Over a year ago

array_intersect is exactly what I was looking for. Thank you!

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